Maybe people should get better at shell, instead. Read the bash / zsh manual. Use ShellCheck.
Shellcode is just a horrible PL, period. Not only it's weird and unlike anything else out there, there's way too many footguns.
One can learn to use it to the point where it's usable to do advanced automation... but why, when there are so many better options available?
Because it’s never going away, and it’s always going to be there. It is the lowest common denominator. Also, a shell script generally doesn’t have any other dependencies (modulo writing one that calls jq or something). No risk of solver hell.
I fully agree with the recommendation to use maintainable code. But that effectively rules out shell scripts in my oppinion. CI shell scripts tend to become big ball of mud rather quickly as you run into the limitations of bash. I think most devs only have superficial knowledge of shell scripts, so do yourself a favor and skip them and go straight to whatever language your team is comfortable with.